1. Field of the Invention
The present invention relates to a trap selector which is used when, among various traps, an appropriate trap must be selected for automatically exhausting condensed water or condensate (drainage), which is produced in steam, compressed air, or at a gas piping system to which said trap is attached.
For example, a steam trap is naturally used as a self-actuated valve which automatically discharges only condensate without losing steam from the steam piping system or steam equipment. Such a steam trap is classified into a mechanical type, a thermostatic type, a thermodynamic type and the like according to its operation principle. There are steam trap types in which the condensate is continuously discharged and those in which it is intermittently discharged. The steam trap may be further classified into various types, such as a trap for low pressure or a trap for high pressure, and a trap with small capacity or a trap with large capacity.
Upon the selection of a steam trap, an optimum one has to be selected so as to meet various working conditions such as steam pressure, steam temperature, condensation rate, the class or the operating state of the device to which the trap in question is attached, or the presence of the condensate for recovery.
2. Description of the Prior Art
One of the conventional trap selectors is disclosed in the Japanese unexamined patent publication (Kokai) Heisei 1-207817 (1989). This trap selector is designed to select an optimum trap which has various uses in such a way that certain data required for the selection of a trap is sequentially inputted in accordance with the indication of a display and program which is previously memorized, the selection of a trap is executed by a microcomputer.
Although the optimum trap can be automatically selected only by inputting the required data into the conventional trap selector, it has a great inconvenience in that the memory inevitably has to be enormous. This problem is caused because one of the most fundamental conditions in the selection of a steam trap or a gas trap resides in selecting a trap provided with enough discharging capability to discharge actual condensate volume and, therefore, all discharging characteristics for every pressure or temperature and the like of various kinds of traps are memorized in the trap selector mentioned above. Thus, a memory with an extremely large capacity is needed. Depending on the temperature of the discharged condensate in the steam trap, degree of reevaporation in the condensate is varied and the discharging characteristic is also changed. As described above, since all the discharging characteristics must be memorized for respective types of conditions in the conventional trap selectors, memory capacity must be further increased. The increase of memory capacity unavoidably causes the cost of the trap selector itself to be raised.